170GHz兆瓦级同轴回旋振荡管的分析计算

Analysis and calculation of a 170 GHz megawatt-level coaxial gyrotron

回旋管是最有希望应用于正在实施的国际热核实验反应堆计划的微波源器件,然而研究设计符合要求的回旋管还存在很多困难需要解决.对170 GHz兆瓦级光滑同轴回旋管的注-波互作用进行了研究.选取模式谱相对稀疏的TE31,12作为工作模式,利用Matlab编制源程序,计算了同轴回旋管的注-波耦合系数、起振电流.在考虑电子速度零散、腔壁电阻率和单模近似的基础上,对光滑同轴谐振腔的优化设计和注-波互作用进行了仿真,给出了磁场、电压、电流和内导体倾角等参量与回旋管效率的关系.结果表明,电压和磁场对回旋管效率影响较大,电子速度零散对回旋管效率影响较小,因而可降低电子枪的设计要求.此外,优化内导体倾角和同轴谐振腔结构参数可提高注-波互作用效率,降低电子速度零散对互作用效率的影响,获得了约50%的电子效率及1.7 MW输出功率.

Gyrotrons are the most promising microwave source devices that can be used in the International Thermonuclear Experimental Reactor, but there are many dificulties to be solved in study and design of gyrotrons to meet the requirements. In this paper, the beam-wave interactions of a 170 GHz megawatt-level smooth-wall coaxial gyrotron are studied numerically. In order to attain high eficiency and stable radiation, TE31,12mode that lies in a relative sparse spectrum is selected as the operating mode, and the beam-wave coupling coeficient and start oscillation current are calculated by a set of source codes developed by Matlab. Taking into account the electronic velocity spread and cavity wall resistivity,and based on a single-mode approximation, the optimization design and simulation of beam-wave interaction of a 170GHz megawatt smooth-wall coaxial gyrotron have been fulfilled. The relationships between eficiency and magnetic field,and the voltage, current, taper angle of insert, and other parameters are presented. Results show that the voltage and magnetic field have great infiuence on eficiency; however, the current and velocity spread do change slightly, thus reduce the requirements of electron gun design. In addition, the optimized taper angle of insert and coaxial cavity geometry parameters can improve the eficiency, reduce the impact of velocity spread on eficiency, and can achieve an electronic eficiency around 50% and an output power 1.7 MW.